Conventional fishing rods cannot adapt to different fishing conditions by permitting adjustment of the stiffness or flexibility of the rod to accommodate such varied conditions. Thus, there is a need for fishing rods in which the stiffness or flexibility of the rod can be adjusted to adapt to varied fishing conditions.
Hollow fishing rods in which the degree of stiffness or flexibility of the rod may be adjusted by adjusting the air pressure within the rod are known in the art. In this respect, U.S. Pat. No. 3,500,570 to Hubbard shows a hollow fishing rod provided with a single-action air pump in the handle to increase or decrease the air pressure inside the rod and thus vary the stiffness or flexibility of the rod.
Hubbard suffers from the disadvantage, however, that the type of air pump used in the device tends to be inefficient because it requires quite a bit of effort to achieve a desired stiffness of the rod. Air pump devices such as those used in the Hubbard fishing rod also tend to be bulky in size and weight, thereby making them awkward to use. Moreover, Hubbard's reliance on air pressure makes the rod susceptible to an unexpected reduction in stiffness due to leakage.
A need therefore exists for a fishing rod in which the stiffness or flexibility of the rod can be more efficiently and easily varied.